Electrical vacuum furnace



1961 T. THELEMARCK 3,004,092

ELECTRICAL VACUUM FURNACE Filed Nov. 9, 1959 Fig. 3

/ I I l I 1 )\U B 22 A -A INVENTOR. 77/07? -r/ A /WWaA wl wz elements of the invention.

United States Patent In the operation of vacuum melting furnaces particularly high-frequency vacuum furnaces it is very important to maintain the required vacuum during the melting process. This requires in turn carefully constructed sealing means for the vacuum tank and the leading through means for the leads supplying current and cooling medium to the furnace coi-l. Nevertheless the furnace tank has .0 be opened easily particularly for the exchange of furnace units, and the connection means for the current and coolant leads in this case have to be loosened and attached in a simple manner. Bare live parts at voltages ice I contain the electric conductors 4 for the furnace coil. I

An annular channel 5 between the hose and the insulated conductor may be used for the supply of cooling water.

' The plate is fixed, again for example, by vulcanization over about 300 volts and vacuum give rise to scintillation phenomena and to a risk of flash-over so that connection means necessary particularly in furnace. arrangements with exchangeable furnace units, and which hitherto have been positioned in the interior of the vacuum tanks are not suitable.

The present invention concerns such furnace arrangements wherein the furnace units after a number of melting processes have to be exchanged due to wear of the lining.

The new structural elements of the furnace arrangement which are the subject matters of the invention are adapted to fulfill the above requirements and are the embodiments of the inventive idea that the bare connection means for the current and coolant leads are mounted outside the vacuum tank. The vacuum tight leading-through means are joined inseparably with the said leads and so placed in a vacuum tight manner into openings in the wall of the vacuum tank that they may be pushed into the interior of the vacuum tank. Consequently new ways have to be made for the construction of the leading-through means, the furnace tank and the supporting means of the furnace unit.

The invention will now be described with reference to the accompanying drawing which shows, by way of example, in FIGURES 1 and 2, a construction of the leading through means. FIGURES 3 and 4 are sections through a vacuum furnace equipped with the structural FIGURE 3 is a cross section through the furnace along the line A-A in FIGURE 4, and FIGURE 4 is a longitudinal section along the line B-B in FIGURE 3, the front connection leads having been taken away.

According to the invention, the connection leads to the furnace unit are led through the wall in a stationary part of the furnace tank and they are connected outside said part to the supply leads for current and coolant by bare connection means.

In order that these connection leads need not be loosened in the interior of the tank when the furnace unit is to be exchanged and to bring about absolutely tight sealing, the leading through means on both sides of the furnace unit are constructed so that they consist of plates of rubber or similar insulating material provided with holes having vulcanized therein hoses of similar material, which contain the electric conductors or serve as pipes for the cooling medium (such as water). The plates are inserted in openings in the furnace tank in such a manner that they may be drawn into the tank.

FIGURES 1 and 2 show a leading-through means according to the invention. A plate 1 of rubber or the to a preferably water cooled steel ring 6 which is inserted in a further ring 7, which is fixed by welding to the openings of the wall of the vacuum tank. A sealing means 9 is placed between the rings 6 and 7. Obviously, some of the hoses may be used for the supply of cooling water only.

The connection leads are attached to the furnace unit as will be seen from FIGURES 3 and 4, and the aim of the invention is that the furnace unit is removed from the furnace tank'together with the connection leads and the leading-through means when the furnace unit is exchanged.

For this purpose the furnace tank is divided into three parts and consists of a part 10 adapted to betaken away, an intermediate stationary part 11, and a cover 12. The furnace unit 13 is supported on one side by'its tilting shaft 14 which rests in bearings 15 supported by brackets 16 which are fixed on the wall of the stationary part 11 of the tank, and on the other side by toothed wheels 17 on a shaft 18 which is journalled in the wall of the movable part 10 of the tank. The wheels are'adapt-ed to engage toothed segments fixed to the furnace unit 13. The movable part ltiis mounted on wheels 20. When the cover 12 is removed the chills may be removed or put in. The bare connection means outside the vacuum tank are designated by 21 in FIGURE 3.

The exchange of the furnace unit is accomplished in that the movable part 10 of the tank is unscrewed and taken away. Hereby the toothed wheels 17 and the toothed segments 19 come out of engagement. In order to preventthe furnace unit from tilting downward about the tilting axis, as pivot an abutment 22 is arranged on the bottom of the stationary part 11. The furnace unit rests against said abutment when the part 10 is taken away. Thereafter, the upper part 23 of the bearing 15 of the tilting shaft 14 is removed, and the leading through plates together with the connection leads fixed therein are drawn into the interior of the furnace tank. The furnace unitis then hoisted from the part 11 of the tank.

The insert-ion of a new furnace unit together with the connection leads and the leading-through plates is accomplished in the inverse sequence.

I claim:

1. Electric vacuum melting furnace, particularly for high frequency, comprising a vacuum tank having a wall, an exchangeable furnace unit accommodated in said tank and having a coil, bare connection means mounted outside the vacuum tank, insulated connection leads for current and coolant leading from the coil of the furnace unit to said connection means, leading-through means of insulating material for said connection leads, the leading-through means for the connection leads being joined inseparably with said leads, the walls of the vacuum tank having openings therein, and means mounting the leading-thro'ugh means in a vacuum tight manner in said openings for movement into the interior of the vacuum tank.

2. Electric vacuum melting furnace comprising a vacuum tank having a wall with an opening therein, an exchangeable furnace unit accommodated in said tank and having a coil, connection means located outside the tank, insulated connection leads for current and coolant leading from the coil of the furnace unit to said connection means, leading-through means for the said connection leads comprising at least one plate of insulating material provided with holes therein covering said opening, leading-through hoses surrounding the connection leads and leading the coolant passing through said holes, said hoses being fixed inseparably to the plate, ring means in which the said plate is fixed inseparably, and sealing means be tween the ring means and the opening in the vacuum tank.

3. Vacuum furnace comprising a vacuum tank having a wall, an exchangeable furnace unit having a coil in said tank, connection means located outside the tank, connection leads for current and coolant leading from the coil of the furnace unit to said connection means, vacuum-tight leading-through means for said connect-ion leads, the vacuumltank comprising three parts, namely, a first part, means mounting the first part for movement away from the tank, a stationary intermediate part and a cover, the movable part being provided with toothed wheels, toothed segments fixed on the furnace unit engaged by said toothed wheels, a tilting shaft for the furnace unit, the stationary intermediate part being provided with supporting means for the tilting shaft and with an abutment for limiting the tilting movement of the furnace unit when the movable part is displaced and the toothed wheels and segments are brought out of engagement with each other.

References Cited in the file of this patent UNITED STATES PATENTS Re. 13,849 Simpson Dec; 15, 1914 1,164,187 Horland Dec. 14, 1915 1,940,256 Krebs Dec. 19, 1933 1,971,195 McKibben Aug. 21, 1934 2,675,414 Capita Apr. 13, 1954.

' FOREIGN PATENTS 439,472 Great Britain Dec. 6, 1955 

